中国有色冶金

More than 70% of the world's lithium resources exist in the form of salt lake brine, and the characteristics of high magnesium-lithium ratio and complex impurity components put forward strict requirements for the selectivity and separation efficiency of lithium extraction technology. This paper focuses on the technology of extracting lithium from salt lake with high Mg: Li ratio (Mg: Li > 500). In view of the problems of poor selectivity and difficult separation in the traditional technology of extracting lithium from salt lake with high Mg: Li ratio （chemical precipitation method and solvent extraction method）, this paper deeply analyzes the emerging technologies of ion sieve adsorption, membrane separation method and coupling lithium extraction from the aspects of molecular action mechanism, crystal structure change and ion migration law, and introduces their application. Ion sieve adsorption is the mainstream technology in the field of extracting lithium from salt lakes at present. Among them, aluminum ion sieve has been industrialized, while manganese ion sieve and titanium ion sieve are still in the stage of laboratory and pilot test. However, due to their excellent saturated adsorption capacities (30-35 mg·g^-1, 15-25 mg·g^-1, respectively, while aluminum ion sieve is only 3-5 mg·g^-1), aluminum ion sieve has been widely used. Lithium ion selective membrane method is a special technology for extracting lithium from salt lakes with high magnesium-lithium ratio, which has the advantages of continuous operation and no secondary pollution, but the flux and stability of membrane materials restrict its industrial application. Coupled lithium extraction technology includes adsorption-membrane separation coupling technology, high gravity enhanced extraction coupling technology, electrochemical intercalation-deintercalation (IDI) lithium extraction technology, etc. , which has the advantages of strong adaptability, high comprehensive benefit and flexible adjustment of process parameters, and is an important development direction of lithium extraction technology in salt lakes with high magnesium-lithium ratio in the future. The adsorption capacity and cycle stability of ion sieve adsorbents can be improved by means of material modification, morphology control and composite modification. In the future, with the research and development of new adsorbents and membrane materials, the optimization of coupling process and the application of intelligent technology, the lithium extraction technology from salt lakes with high magnesium-lithium ratio will achieve leap-forward development, providing a solid resource guarantee for the sustainable development of global new energy industry.